The present invention relates to a label applicator. More particularly, the present invention pertains to a spring mount for a label applicator tamp pad.
Automated label applicators or label machines are well known in the art. A typical machine feeds a continuous web of label material (which web material includes a carrier or liner and a series of discrete labels adhered to the liner at intervals along the liner), removes the labels from the liner and applies the labels to the objects. In many such machines, the label is also printed by the device, prior to separation from the liner and application to the objects.
Known label machines include, generally, a supply roll on which the web is wound. The web is fed from the supply roll around a plurality of rollers and enters a printing head. In the printing head, indicia are printed on to the individual labels. The web exits the print head and the labels are separated from the liner and are urged into contact with a tamp pad.
The tamp pad is, typically, a vacuum assisted assembly that holds the individual labels and moves the labels into contact with the objects onto which they are adhered. Tamp pads are typically designed to apply a predetermined or desired force upon application of the label to the object. The force used to apply the label can be varied depending upon the object. For example, while a relatively larger force can be used to apply a label to a heavy gauge shipping carton, a much lesser force must be used when applying a label to, for example, a bakery carton.
In operation, the label is separated from the liner and is held on the tamp pad. The label remains on the pad until the target object is in line with the pad. A tamp cylinder then extends to move the tamp pad into contact with the object surface to apply the label to the surface. At the completion of the extension stroke, the cylinder returns the pad to the home or rest position at which time a subsequent label can be fed onto the tamp pad. In many known arrangements, the tamp pad is rigidly mounted to the extendable cylinder rod.
Tamp pads are configured such that a label is transferred onto the pad after it is separated from the liner with the non-adhesive side of the label contacting an impact plate (on the front side of the pad). The label is held on the plate and the tamp pad is extended toward the product surface for application of the label. In a typical arrangement, a vacuum is used to secure the label to the impact plate. Typical impact pads are formed from a low friction material having a plurality of vacuum openings formed therein. Vacuum channels formed in the rear of the plate permit the transfer of vacuum to the front surface of the impact plate to secure the label to the plate.
In that it is desirable to transfer the label and apply the label to the product surface at a relatively high rate of speed, the transfer process inherently controls the throughput of the label machine. However, the objects to which the labels are applied may not necessarily be properly oriented on the object line path. That is, the cartons may not all lie straight on the machine line such that the plane of the panel onto which the label is applied is perpendicular to the direction of extension of the cylinder. As such, labels can be misapplied or less than fully applied to the carton panel.
One known arrangement to accommodate a slightly askew carton includes a tamp pad that is mounted to a mounting plate by a plurality of corner mounted springs and shoulder bolts. While such an arrangement serves to accommodate carton skew to a point, it requires a complex arrangement of bolts and springs, as well as a complex arrangement for the traverse of vacuum tubes and the like to provide the necessary structural vacuum connections to the tamp head. Moreover, with this type of mount, as the angle at which the pad contacts the carton increases, the pad xe2x80x9crotatesxe2x80x9d away from a plane perpendicular to the direction of extension of the cylinder.
When the angle increases too greatly, the edges of the pad around the bolt openings can bind on the bolts. In such an event, the pad can become xe2x80x9cstuckxe2x80x9d on the bolts at an angle. This, of course, would require that machine operation be halted so that the pad can be readjusted to the desired, perpendicular orientation. Given that the label applying operation is a relatively high speed operation, this could have a substantial adverse impact to machine and/or line operations.
Accordingly, there exists a need for a tamp pad mount that accommodates the skew of a carton panel or other object onto which the label is applied. Desirably, such a mount is biased to a perpendicular orientation, and is readily moved from the perpendicular position to properly apply the label to the panel. More desirably, such a mount is simple in design, prevents binding at an undesirable angle, and can be fitted onto existing label applicator machines.
A swivel mount is configured for mounting a tamp pad to a label applicator of the type for receiving a label at a first retracted position and applying the label to an object at a second, extended position. The mount permits the application of a label to an object, such as a carton panel and accommodates the skew of the carton panel or other object. Such a mount is biased to a perpendicular orientation, and is readily moved from the perpendicular position to properly apply the label to the panel.
The mount includes a mounting block for fastening to the tamp pad. The mounting block has a bore therein having an inner, open cross-sectional region and defines a retaining region therein. In a current embodiment, the retaining region is configured as a collar.
A knuckle fitting is received within the bore and engages or seats in the retaining region. The knuckle fitting has an increasing cross-sectional area that is, at its largest point, larger than the open cross-sectional area of the retaining region. In this manner only a portion of the knuckle fitting extends beyond the collar, while another portion of the knuckle fitting is maintained within the bore.
In a present embodiment, the knuckle has tapered side walls and the collar has mating side walls. A present taper angle is about 20 degrees. In this arrangement, the knuckle fitting has a frusto-pyramidal shape, and preferably a square frusto-pyramidal shape. The corners defined by the frusto-square pyramidal shape can be rounded.
A spring is positioned to provide a force against the knuckle fitting at an end of the second portion. The spring seats the knuckle fitting within the collar. Preferably, the spring is centrally disposed relative to a longitudinal axis or plane through the mount.
To maintain the spring and knuckle fitting within the mounting block, a cover can be positioned on the mounting block extending over the bore and the spring. The cover further assures that the spring force acts on the knuckle fitting maintaining the fitting centered within the block.
A present knuckle fitting is formed from an aluminum alloy, such as alloy 7075-T6 with a hardcoat anodized finish. Such a material provides the strength, durability and wear resistance needed for such a part in a high cycle environment.
The present mount permits movement of the tamp pad from an orientation perpendicular to a direction of movement between the retracted and extended positions to an orientation inclined relative to the direction of movement. Moreover, it permits such movements, and facilitates return to the perpendicular orientation, in a relatively light weight and efficient, yet simple design. Further, the present mount has been found to overcome many of the problems of known designs, other than complexity, such as pad binding and sticking.
These and other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the appended claims.